#define  _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <string.h>
int main()
{
	char a[501];
	scanf("%s", a);
	char b[501];
	strcpy(b, a);
	int i = 0, count = 0;
	int len = strlen(a);
	for (i = 0; i < len; i++)
	{
		int j = 0;
		for (j = 0; j < len; j++)
		{
			if (j == i)
				continue;
			if (a[j] == a[i])
			{
				a[j] = -1;
			}
		}
	}
	for (i = 0; i < len; i++)
	{
		if (a[i] != -1)
			count++;
	}
	printf("%d", count);
	return 0;
}